1. Field of the Invention
The present invention relates to a combination lens assembly and system useful in eyewear frames, and more particularly, relates to an optical lens assembly which comprises a plastic lens member in combination with a glass lens member.
2. Description of the Art
Eyewear, such as sunglasses or spectacles, have been known and used for hundreds of years. The lenses used in eyewear have conventionally been made of glass and, more recently, been made of various plastic materials such as polycarbonate.
Glass lenses generally have optical benefits, such as optical clarity, and are highly scratch resistant when compared to plastic lenses. However, glass lenses tend to be heavy and are generally less desirable for use during athletic activities since they are not fully shatterproof. Since plastic lenses are light weight and can be made to be substantially impact resistant, they are typically the preferred choice for lenses used with eyewear intended for use during athletic activities. However, plastic lenses generally do not have the optical clarity of glass lenses and have a tendency to scratch easily. Thus, it would be desirable to combine the optical add scratch resistant properties of glass with the light weight and impact resistant properties of plastic in order to have lenses which exhibit the best properties of both materials.
In fact, many attempts have been made to physically combine plastic and glass lenses. Conventional approaches to develop combination lenses typically resulted in laminates or composites which include both plastic and glass components. Generally, the glass and plastic components are held together by means of an organic adhesive such as an epoxy. While this approach would appear simple and straightforward, it has proven to be time consuming and expensive and requires extreme care in selecting proper adhesives in order to avoid stress conditions that develop between the glass component and high expansion plastic components. Thus, laminated or composite lens structures have not proven to be commercially satisfactory.
The present invention provides a unique combination lens assembly which is light weight, safe to wear during any athletic activity, and inexpensive and simple to manufacture.